The present disclosure generally relates to a process for manufacturing semiconductor structures, and particularly to methods for sidewall image transfer employing a dielectric cap material layer on top of a metal nitride layer.
A sidewall image transfer (SIT) process as known in the art employs a titanium nitride layer as an etch mask for transferring a composite image of two independent images. An organic planarizing layer (OPL) is formed directly on the titanium nitride layer, and is consumed during the transfer of the composite pattern into the titanium nitride layer. The OPL tends to be consumed during the pattern transfer into the titanium nitride layer, resulting in distortion or loss of fidelity in the transferred pattern in the titanium nitride layer. A method of enhancing the fidelity of pattern transfer during a SIT process is desired.